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Comment by SJMH | Hacker News Reader

They mention 1/3 of the nodes. How much of a weakness is this?

How does that prevent me from pretending to be any number of nodes I want; including, but by no means limited to, over 1/3 of the nodes? (Maybe you should first do a quick search to learn what a Sybil attack actually is?) They can shore this up by having some kind of Sybil attack prevention elsewhere, but given their statements about proof-of-work here it seems unlikely they would, for example, add proof-of-work elsewhere. It might be, based on skimming some blog post I found if theirs, that the goal of this is to help them shore up a proof-of-stake algorithm to deal with byzantine failures? That would be interesting, but is a more involved scheme then than just this part, and I actually don't think that is what they are doing either (as the connection in that blog post is mostly me reaching for something that works, not a direct connection made by the authors).

For SAFE Network, this is handled, I believe. Other networks that implement PARSEC will need to address it in some similar way.

In the case of SAFE, you can generate as many nodes as you want, but they must be valid nodes (doing the work that the network asks of them) for a long time before being promoted to a status that allows them to participate in consensus of a section. Any misbehavior on their part results in demotion or failure to be promoted. So each node would need to be a legitimate contributor to the network, with all that that entails, before being promoted to a status where their later misbehavior would matter. You would be creating real nodes, that used real bandwidth and real CPU resources and did real work that benefits the network, in order to infiltrate your evil nodes into the network. So, not an insubstantial cost to you.

Your nodes will be assigned into sections randomly, so it will be very difficult for you to manage to get multiple nodes with voting status, into a single section, and staggeringly difficult to get enough such that your nodes constitute 1/3rd of that section. Of course, exactly how difficult depends on network size (number of sections).

Finally, even once a node is assigned into a particular section, it will be reassigned to another random section at some interval, further decreasing your ability to take over a particular section.

> Finally, even once a node is assigned into a particular section, it will be reassigned to another random section at some interval, further decreasing your ability to take over a particular section.

Doesn't that on the flipside also mean that given enough time your malicious nodes will end up in the same section, allowing for a take over of that section?

Yes, I believe that there is a non-zero probability that could happen, just as there is a non-zero probability that all the air molecules in the room you are in, which are bouncing around randomly, may all end up in the other corner of the room and suffocate you.

Since all nodes change sections randomly, like air molecules, they should remain randomly distributed, provided the network size is large enough. For a small network though, one can imagine you could get lucky eventually. Like other decentralized networks, security and size are related.

As the network grows it becomes increasingly harder to do so, especially since you need to add increasing amounts of resources (bandwidth, disk space, and some cpu, for the proof-of-resource) to your attack.

This is not too dissimilar to what happens with CPU-only PoW consensus networks. Easy to attack in the beginning but less so as the network grows.

It will be interesting to see how the SAFE network will be bootstrapped. I'm sure there will be a significant number of malicious players waiting in line to disrupt it early on.

If it works, and I believe it can, IMHO this network will be one of the most important developments in decentralised systems in the past decade.

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